Implementation of Synchronous Bidirectional Converter Using a Fuzzy Logic Controller

Abstract

A bidirectional converter is necessary for power transfer between two different voltage levels. This paper describes the implementation of the combined conventional buck and boost converter as the bidirectional converter, using the fuzzy logic controller as the control algorithm. The intrinsic diode of the MOSFET is used when the MOSFET is not in conduction mode, these diodes work as a conventional diode in each power conversion mode. The synchronous switching mode for both MOSFETs reduces the power losses during the switching due to the low R_DS of the MOSFET over conventional diodes. Analyzing the parasitic resistance for both passive and active components helps optimize the component’s parasitic parameters to obtain optimal efficiency. The design of the fuzzy logic controller consists of fuzzy rules with the Mamdani inference system and membership function parameter tuning to achieve the best performance on low overshoot and fast transient response. The fuzzy logic controller is designed as a single controller to be compatible with both power conversion directions. The optimized design of only 8 fuzzy rules proved to be efficient for a fast microcontroller runtime with a robust transient response. The bidirectional converter can achieve up to 96% efficiency for the buck mode of 290W and 91% efficiency for the boost mode of 260W.